1. Field
Apparatuses consistent with exemplary embodiments relate to a fluid machine, and more particularly, to a fluid machine having improved aerodynamics performance and reduced noise generation.
2. Description of the Related Art
Compressors, expanders, or pumps, which compress or expand fluid, have a fluid machine using a rotation element. A fluid machine has an impeller as a rotation element. The impeller transfers rotational dynamic energy to fluid thereby increasing the pressure of fluid. The impeller includes a plurality of blades that guide movement of fluid and transfer energy to the fluid.
A shroud is arranged outside the impeller, and the shroud forms a passage for passing fluid together with the blades. In order to design a fluid machine having superior performance, aerodynamics performance in the passage formed by the impeller and the shroud needs to be enhanced.
However, during an operation of the impeller, high pressure is generated by the fluid such that loud noise is generated between the impeller and the shroud. There have been many trials to reduce noise from operation of the impeller. However, when a separate apparatus is installed on the impeller or the shroud to reduce noise, aerodynamic loss is generated in the fluid machine.
Accordingly, there is a demand for technology to be developed for reducing noise and simultaneously maintaining superior aerodynamics performance in the passage between the impeller and the shroud for passing fluid in the design of a fluid machine.
U.S. Pat. No. 5,256,031 discloses that a groove is formed on a casing wall to reduce vibration. However, a groove-forming technology such as this seriously increases aerodynamic loss.
Japanese Publication No. 2007-218147 discloses technology by which a hole is formed in a shroud to reduce noise. As such, a simple structure in which a hole is formed in a wall of the shroud seriously increases aerodynamic loss.
Japanese Publication No. 2002-537184, Korean Publication No. 1998-0060499, and U.S. Pat. No. 4,540,335 disclose technologies using a hole to improve noise or improve flow rate properties. In these technologies, however, because a structure is used in which a hole is formed at a position of a casing corresponding to a tip (end portion) of a rotating blade, it is difficult to apply the structure to improve aerodynamics performance and reduce noise in a fluid machine using a shroud covering an upper surface of a rotating blade.